Foi uma combinação de geografia (no núcleo central do mundo), geografia espacial (encruzilhada hiperlane) e história (veja abaixo)
Coruscant was a planet located in the Core Worlds. Located at the intersection of numerous major hyperlanes— including the Perlemian Trade Route, the Corellian Run, the Metellos Trade Route, the Koros Trunk Line, and the Leisure Corridor—its hyperspace coordinates were (0,0,0) which effectively made it the center of the galaxy. (src)
No que diz respeito à história, "The New Essential Chronology" afirma que
The planet was considered by many to be the Human homeworld, and was known as Notron early in its history. It has been speculated that at some point, the Celestials transplanted humans from Coruscant in order to populate Corellia and other human societies on different planets throughout the galaxy.
Além disso, Alderaan foi colonizado de Coruscant (mesmo Wookiepedia)